b612
16c62a97d5
- 新增时标、ΔT 模型、质心时间与 UT1 支持 - 改进日月食、月掩、行星事件及路径边界计算 - 完善恒星三维自行与动态距离传播 - 扩展 SVG、GeoJSON、KML 输出与底层距离换算工具 - 整理中英文手册、示例资源及回归测试
80 lines
2.8 KiB
Go
80 lines
2.8 KiB
Go
package svg
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import (
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"fmt"
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"html"
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"math"
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"strings"
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"b612.me/astro/internal/svgchart"
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)
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// localOccultationOverviewLabel 是总览区一个接触标签：文本与它在图上的接触点位置。
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type localOccultationOverviewLabel struct {
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text string
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x, y float64
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}
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// writeLocalOccultationOverviewLabels 排布总览区的接触标签：先按原偏移试位，压叠时沿接触点径向
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// 外推、再上下错开，仍放不下就贴着月球外缘排成竖列；离接触点较远的标签用细引线连回去。
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func writeLocalOccultationOverviewLabels(
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b *strings.Builder,
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labels []localOccultationOverviewLabel,
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table *svgchart.LabelTable,
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cx, cy, moonRadius float64,
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color string,
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) {
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if len(labels) == 0 {
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return
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}
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const fontSize = 11.0
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spillTop := cy - moonRadius - 24
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spill := 0
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for _, item := range labels {
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anchor, side := "start", 1.0
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if item.x > cx {
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anchor, side = "end", -1
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}
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baseY := item.y - 9
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if item.y < cy-20 {
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baseY = item.y + 15
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}
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candidates := []svgchart.LabelPlacement{{X: item.x + side*8, Y: baseY, Anchor: anchor}}
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ux, uy := item.x-cx, item.y-cy
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if norm := math.Hypot(ux, uy); norm > 1e-9 {
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ux, uy = ux/norm, uy/norm
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} else {
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ux, uy = 0, -1
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}
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for step := 1; step <= 5; step++ {
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reach := 12 + float64(step)*13
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candidates = append(candidates,
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svgchart.LabelPlacement{X: item.x + ux*reach + side*6, Y: item.y + uy*reach, Anchor: anchor},
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svgchart.LabelPlacement{X: item.x + ux*reach - side*6, Y: item.y + uy*reach, Anchor: svgchart.MirrorLabelAnchor(anchor)},
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)
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}
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for step := 1; step <= 4; step++ {
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candidates = append(candidates,
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svgchart.LabelPlacement{X: item.x + side*8, Y: baseY - float64(step)*15, Anchor: anchor},
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svgchart.LabelPlacement{X: item.x + side*8, Y: baseY + float64(step)*15, Anchor: anchor},
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)
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}
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placement, placed := table.Place(item.text, fontSize, candidates)
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if !placed {
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placement = svgchart.LabelPlacement{X: cx + side*(moonRadius+30), Y: spillTop + float64(spill)*15, Anchor: anchor}
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for spill < 40 && table.OverlapsText(placement.X, placement.Y, fontSize, item.text, placement.Anchor) {
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spill++
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placement.Y = spillTop + float64(spill)*15
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}
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table.ReserveText(placement.X, placement.Y, fontSize, item.text, placement.Anchor)
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spill++
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}
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if math.Hypot(placement.X-item.x, placement.Y-item.y) > 16 {
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fmt.Fprintf(b, `<line x1="%.3f" y1="%.3f" x2="%.3f" y2="%.3f" stroke="%s" stroke-width="0.7" opacity="0.7"/>`,
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item.x, item.y, placement.X, placement.Y, color)
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}
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fmt.Fprintf(b, `<text x="%.3f" y="%.3f" fill="%s" stroke="#ffffff" stroke-width="3" paint-order="stroke" font-family="Arial, sans-serif" font-size="%.0f" font-weight="700" text-anchor="%s">%s</text>`,
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placement.X, placement.Y, color, fontSize, placement.Anchor, html.EscapeString(item.text))
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}
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}
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